If you set up a sub floor consider running heating through it. Heated pipes all over the place in the sub floor could really help!
My fish room is more of a greenhouse style, and I am having heating issues. I sure wish I had the money to elevate the floor and plumb it for heat!
I several stands in there:
Factory built cabinet style stands
DIY wood stands
Concrete block stands.
Steel shelving with plywood shelves (came with particle board which did not last at all)
The floor gets wet, but does not stay wet. Still, the factory cabinet stands are showing a bit of damage from the dampness. My home made wood stands are holding up just fine. Different sort of wood. Of course the concrete block stands have no problem when the floor is damp. The steel stands are OK, they are actually up on concrete blocks. There is a hint of rust here and there, but so little that it is not a problem at this point. If I take down any of these they can be sanded and re-painted.
Make sure you get 'ground contact' pressure treated wood. There are different grades sold in different areas. Talk to a proper lumber expert about what is the best for your area. In our area we use ACQ .40 for most ground contact, but ACQ .60 is available, if it is specified by an engineer. I do landscape design that involves quite a bit of construction, including retaining walls and other things that are in contact with the soil.